The  common  wisdom  is that  all  stars  in  an  open  cluster  are  expected  to share  the  same chemical abundance pattern. This is a fundamental assumption of the concept of chemical tagging: the ability to identify which stars were born together even the stars are now dispersed throughout the Milky Way. However, recently we have found that this may in fact not be the case,  which  would  have  far-reaching  implications.  Our  team  has  developed  a differential analysis technique that has led the field of stellar chemical abundances to unprecedented precision, ~ 2%, a five-fold improvement over traditional analyses. Our study on the Hyades revealed  that this open  cluster  is chemically  inhomogeneous  at the 0.02 dex level,  which could be due to pollution of gas before complete mixing of the proto-cluster cloud. Our recent study on the M67 showed a clear signature of atomic diffusion to be ~ 0.1 dex through the evolution stage in this benchmark open cluster. Our results thus provide significant new constraints on the chemical composition of open clusters and a challenge to the current view of Galactic archeology.

～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～

本通知也可以在云台学术报告网页看到：

/xwzx/xstg/

申请安排学术报告的同事请参见台学术报告管理办法：

/xwzx/xstg/gzzd/